Earth's Layers and Plate Tectonics Quiz

Grade 9 · Science · Quiz

Test your knowledge of Earth's interior structure and plate tectonic theory with 10 questions.

Questions

1. From the center outward, what is the correct order of Earth's layers?

   1. Crust, mantle, outer core, inner core
   2. Inner core, outer core, mantle, crust
   3. Mantle, crust, outer core, inner core
   4. Outer core, inner core, mantle, crust
   Show answer

   Answer: Inner core, outer core, mantle, crust

   Earth's layers from center out: inner core (solid Fe-Ni) → outer core (liquid Fe-Ni) → mantle (semi-solid rock) → crust (thin solid surface). Think of it like a hard-boiled egg.

2. The theory of plate tectonics was widely accepted the moment Alfred Wegener proposed it in 1912.

   Show answer

   Answer: False

   Wegener's continental drift hypothesis was largely rejected during his lifetime because he couldn't explain the mechanism. It wasn't until the 1960s when seafloor spreading was discovered that plate tectonics gained wide acceptance.

3. The layer of Earth where convection currents drive plate movement is the ___.

   Show answer

   Answer: mantle

   The mantle makes up about 84% of Earth's volume. Heat from the core sets up convection currents in the semi-solid mantle rock, which drag the overlying lithospheric plates.

4. Where are most of the world's earthquakes and volcanoes concentrated?

   1. Mid-Atlantic Ridge only
   2. Random locations on Earth
   3. The Ring of Fire around the Pacific
   4. Near the equator
   Show answer

   Answer: The Ring of Fire around the Pacific

   The Ring of Fire traces the boundaries of the Pacific Plate. About 90% of earthquakes and 75% of volcanoes occur here because of the intense tectonic activity at these convergent and transform plate boundaries.

5. When an oceanic plate collides with a continental plate, the oceanic plate usually:

   1. Floats on top
   2. Subducts beneath the continental plate
   3. Moves sideways
   4. Dissolves
   Show answer

   Answer: Subducts beneath the continental plate

   Oceanic crust is denser (basaltic) than continental crust (granitic). At convergent boundaries, density wins — the heavier oceanic plate sinks (subducts) beneath the lighter continental plate, forming a trench and often triggering volcanoes.

6. New oceanic crust is created at divergent boundaries through seafloor spreading.

   Show answer

   Answer: True

   At divergent boundaries, plates pull apart and magma rises to fill the gap, cooling and hardening as new oceanic crust. This seafloor spreading pushes older crust outward from the ridge — evidence that led to plate tectonic theory.

7. The Mariana Trench, the deepest place on Earth, was formed at a:

   1. Divergent boundary
   2. Transform boundary
   3. Convergent boundary
   4. Hot spot
   Show answer

   Answer: Convergent boundary

   The Mariana Trench (11 km deep) formed where the Pacific Plate subducts beneath the Mariana Plate. The downgoing slab creates the deep trench — the deepest point on Earth's surface.

8. The rigid outer layer of Earth, made of the crust and upper mantle, is called the ___.

   Show answer

   Answer: lithosphere

   The lithosphere is Earth's rigid outer shell (crust + uppermost mantle). Below it is the asthenosphere — a more plastic region of the mantle over which the lithospheric plates slide.

9. What evidence supports the theory of continental drift?

   1. Matching fossils on different continents
   2. Similar rock formations across oceans
   3. Complementary coastline shapes
   4. All of the above
   Show answer

   Answer: All of the above

   Continental drift is supported by multiple independent lines of evidence: matching fossils of the same species on now-separated continents, identical rock formations, and the jigsaw-puzzle fit of coastlines (especially South America and Africa).

10. Which layer of Earth is in a SOLID state despite being extremely hot?

    1. Outer core
    2. Mantle
    3. Inner core
    4. Asthenosphere
    Show answer

    Answer: Inner core

    Despite temperatures of ~5,000°C, the inner core is solid due to immense pressure from the overlying layers compressing the iron-nickel alloy. The outer core is liquid because pressure is lower there.

Get a personalized course on Earth's Layers and Plate Tectonics built around your child.